Ok, did that test. No test light illumination. To redbull-1 (and both of you guys, for that matter): I DID Have continuity from the ECM down to the under seat connector for the O2 (this was along the black wire with white tracer). You guys are a huge help. Thank you so much!!!

PS- the car is an EX-L Coupe.. no navigation. The diagrams and connector locators were SUPER HELPFUL!!! 😁

 

The problem with the continuity test is the volt meter sends a very low current through the wire. If the wire has a few strands left, the volt meter will show a continous circuit, but the remaining diameter of the wire can't carry the current in the cirucit.

I'm not sure if you fixed the issue yet. If not, you'll have trace the wire harness from under the seat to C551 to find the damaged area. Fortunately, the section of wire harness is pretty short. The plastic harness cover might be rubbing through and the wire got damaged. The harness goes under the plastic/carpet on the passenger door, so you'll have to pull up that plastic piece at the bottom of the passenger door opening. I think you'll have to pull back the rubber seal as well.

 

No, I haven’t fixed it yet. OK, I’m gonna open up that section of harness. The carpeting and seat is out since there is a significant water leak from the moonroof which soaked the floor. I’m wondering if that contributed to the issue.

I’ll be back with the thread once I see what the wiring looks like.

 

Alright guys. I JUST looked at the black w/ white tracer wire from the O2 connector side up to the C551 connector. No breaks or issues with the wire. Honda used black and also gray tape in the factory harness? It looked factory, but also kinda janky for a Honda mfr. Plus, there is a splice at the white w/ red tracer wire right near the O2 sensor under seat connector. That was wrapped by gray tape. Solid factory splice, but strange looking with conductor showing. It’s as if they heat sealed it together at the factory.